In many types of agricultural working machines, a working implement is fastened to a self-propelled carrier vehicle. The working implement that is arranged, for example, for the harvesting of plants, can be repositioned in height in many cases, in order to be able to preset the working height above the ground. Alternatively the contact force of the working implement on the ground may be variable. As a rule, working implements of this type can be moved into a non-operating position for purposes of transportation.
EP 1 051 895 A describes an agricultural working machine in the form of a mowing implement. The mowing implement is provided with several working units that are mechanically separated from each other, with mowing arrangements, that can be pivoted upward by hydraulic cylinders into their transport position. Hydraulic fluid can be applied to a controlling lifting cylinder arranged between the carrier vehicle and the working machine which is thereby brought into the transport position. In order to pivot from the transport position into the working position, the hydraulic fluid is drained from the hydraulic cylinders of the working units. An elastic accumulator is connected to the hydraulic cylinder of the working unit in order to provide the function of a shock absorbing damping element that controls the working unit that contacts the ground in the working position. During the pivoting from the working position into the transport position, the damping element is separated from the hydraulic cylinder by a shut-off valve. In order to guarantee that the shut-off valve remains in the closed position as long as the working units remain in the raised position, a pressure sensor is provided that generates a signal as a function of the pressure holding the working units in the upward position, which keeps the shut-off valve closed as long as the pressure is maintained. After undershooting a threshold value of the pressure, the shut-off valve is again opened after the lowering of the working units. Then, the working units have been folded down, and the pressure established by a safety valve in the cylinder defines the contact pressure, and the damping element absorbs any possible shock loads. Thereby, the damping element is connected to the hydraulic cylinder that pivots the working units only when the working units are in the working position.
In the known working machine it is seen as a disadvantage that a controlling lifting cylinder is required for the raising and lowering of the working units. The lowering of the working units is rather time-consuming, since the pressure in the hydraulic cylinder drains away relatively slowly as the weight of the working units is used to move the hydraulic cylinder. Finally, all three working units always move simultaneously so that the working process of the working units, that are arranged behind each other in the direction of operation, does not occur in a straight line. Thereby, difficulties can occur, for example, in the case of swaths lying perpendicular to each other.
The problem underlying the invention is seen in the need to define an improved movement system for a working implement in which the aforementioned problems have been overcome.